| The plot follows detectives Karl Roebuck and Elise Wasserman working together to find a serial killer who left the upper-half body of a French politician and the lower-half of a British prostitute in the Channel Tunnel, at the midpoint between France and the UK. They later learn that the killer—who comes to be nicknamed the "Truth Terrorist"—is on a moral crusade to highlight many social problems, terrorising both countries in the process |
| Name | Character | Episodes |
|---|---|---|
| Clémence Poésy | Élise Wassermann | 24 |
| Stephen Dillane | Karl Roebuck | 24 |
| Thibault de Montalembert | Olivier Pujol | 24 |
| Cédric Vieira | Phillipe Viot | 24 |
| Angel Coulby | Laura Roebuck | 16 |
| William Ash | Boleslaw 'BB' Borowski | 14 |
| Keeley Hawes | Suze Beaumont | 10 |
| Joseph Mawle | Stephen Beaumont | 10 |
| James Frain | Kieran Ashton / John Sumner | 10 |
| Jack Lowden | Adam Roebuck | 10 |
| Tom Bateman | Danny Hillier | 10 |
| Tobi Bakare | Chucks Akinade | 10 |
| Catalina Denis | Veronica | 10 |
| Mathieu Carrière | Alain Joubert | 10 |
| Jeanne Balibar | Charlotte Joubert | 10 |
| Caroline Proust | Anne-Marie Delgado | 10 |
| Thierry Frémont | Fabien Vincent | 10 |
| Hannah John-Kamen | Rosa Persaud | 8 |
| India Ria Amarteifio | Maya Roebuck | 6 |
| Edyta Budnik | 5 | |
| Nicholas Burns | Richard Carver | 2 |
| Harriet Turnbull | Isla Carver | 2 |
| Hero Fiennes Tiffin | Leo | 1 |